IgA nephropathy is a common type of primary glomerular disease, first reported by Berger in 1968. At that time, its typical clinical manifestations and immunological findings included recurrent hematuria, IgA deposition in the glomerular mesangial region, and a favorable prognosis. Over more than 30 years of clinical and experimental research, it has been found that in addition to recurrent hematuria, other clinical manifestations may also occur. Some cases may even experience a decline in renal function, progressing to chronic renal failure. Given that certain systemic diseases (such as liver disease) can also lead to IgA deposition in the glomerular mesangial region, the term "IgA nephropathy" clinically refers only to those cases without a clear underlying disease cause.

bubble_chart Pathological Changes

The findings primarily show mesangial proliferation, which can be diffuse or focally segmental in distribution. Immunofluorescence reveals significant IgA deposition in the mesangial region, along with possible IgG and C3 properdin deposition, though the fluorescence intensity is weaker than that of IgA. Electron microscopy shows electron-dense deposits in the mesangial area.

bubble_chart Clinical Manifestations

Typical manifestations

Children often present with recurrent episodes of gross hematuria. The onset of gross hematuria frequently coincides with or occurs within 1–2 days of nonspecific respiratory or gastrointestinal infections. A minority of cases may follow physical exertion, fever, tonsillectomy, tooth extraction, or trauma. Typically, gross hematuria resolves rapidly within a few days. During episodes of gross hematuria, there is no edema, hypertension, or other discomfort; some older children may complain of lumbago. Hematuria can recur multiple times, with varying intervals between episodes. Urinalysis during remission may be normal or show persistent microscopic hematuria. Renal function tests are normal, and some children may exhibit elevated serum IgA levels.

Other manifestations

Although recurrent hematuria is the most common presentation of IgA nephropathy in children, other clinical variants may occur, such as:

1. Onset with acute nephritic syndrome, characterized by hematuria accompanied by edema and hypertension.
2. Prominent proteinuria at onset or during disease progression, sometimes reaching nephrotic syndrome levels, or presenting with massive proteinuria and hypoalbuminemia typical of nephrotic syndrome.
3. Insidious onset, incidentally detected during routine urinalysis, which may subsequently follow a protracted nephritis course or progress to chronic nephritis.
4. Rare cases may present as rapidly progressive glomerulonephritis, malignant hypertension, or hypokalemic nephropathy.

bubble_chart Diagnosis

This condition is actually an immunopathological diagnostic term. There are three diagnostic criteria:

1. Renal biopsy immunopathological examination (using immunofluorescence or enzyme labeling) shows significant IgA deposition in the glomeruli, with fluorescence intensity IgA > IgG and C3.
2. The IgA deposition is mainly limited to the glomerular mesangial or paramesangial areas, but may also extend to the capillary loops.
3. Systemic diseases known to cause IgA deposition in the glomerular mesangium (such as Henoch-Schönlein purpura, liver diseases, etc.) must be excluded.

bubble_chart Treatment Measures

There is no specific treatment for this condition.

1. For those with infections, appropriate treatment is given. For those with chronic tonsillitis as a focus, most advocate removing the focus, which may reduce episodes. For those with a history of food allergies, reducing the intake of such foods is recommended.
2. Phenytoin sodium at 5–6 mg/(kg·d) orally has been reported to reduce episodes in children with episodic hematuria, or the antiallergic drug disodium cromoglycate may be used.
3. For those with urinary protein >1 g/d, adrenal corticosteroids or a combination with immunosuppressants may be used, which may protect or delay the deterioration of renal function (specific doses are detailed in the nephrotic syndrome section).
4. Other treatments include the use of Root Leaf or Flower of Common Threewingnut or Tripterygium hypoglaucum. Some anticoagulants such as dipyridamole and Salvia may help alleviate hematuria. For those with existing hypertension, antihypertensive treatment should be administered.

bubble_chart Differentiation

1. Differentiate from glomerular diseases that can clinically cause hematuria by first excluding non-glomerular hematuria based on the morphology of red blood cells in the urine. For glomerular hematuria, distinguish between conditions such as acute post-streptococcal glomerulonephritis, thin basement membrane disease, hereditary nephritis, purpura nephritis, lupus nephritis, hepatitis B virus-associated nephritis, etc.
2. Differentiate from other diseases that pathologically cause IgA deposition in the mesangial region, such as allergic purpura, systemic lupus erythematosus, liver cirrhosis, post-portosystemic shunt, hepatitis, ankylosing spondylitis, etc.